The new Database.com service unveiled by Salesforce aspires to be the database engine for cloud application developers

What a URL! Database.com sounds like a service with grand ambitions of becoming the back end for the entire Internet, a notion that showman extraordinaire Marc Benioff, CEO of Salesforce, would do little to discourage.

In fact, all Salesforce is doing is opening up the same giant database-as-a-service it already uses to power the Salesforce CRM application itself -- and offering a full complement of developer tools and security controls to go with it. Instead of subscribing to Salesforce, you subscribe to Salesforce's back end. It's similar in spirit to what Amazon did when it decided to make its infrastructure available to subscribers through Amazon Web Services.

The idea harkens back to the early days of Web services, when visionaries became infatuated with the idea of the Internet as the ultimate application development environment. You can think of a database-as-a-service in the cloud as the cornerstone of that environment. But immediately, a few questions come to mind:

Who is going to hand over their precious data to Database.com? This is the perennial question for SaaS (software as a service) in general. More companies have become accustomed to the idea -- after all, credit card information and payroll data is handled by third parties all the time -- but Database.com does seem to raise the stakes. Sensitive data from all kinds of companies in one place with open APIs? It sounds like a Russian hacker's dream.

How will Salesforce protect all that data? Salesforce would argue that the stakes aren't being raised at all. This is the same Oracle database Salesforce uses to serve its customers, with no major data breaches in the public record (although there was this minor phishing incident in 2007). Naturally, SSL is part of the deal, although Salesforce will be charging an extra $10 per user per month for its Enterprise Services, which include user identity, authentication (using oAuth or SAML), and row-level security access controls.

Waita minute, doesn't Salesforce already offer a database in the cloud? Why yes, it does. As part of its Force.com platform as a service, it's simply called the Force.com database. But Database.com is a relational monster that will purportedly handle almost any task you'd throw at a full-blown, locally installed version of Oracle. And you don't need to subscribe to Force.com in order to use it -- although Salesforce hastens to add that Force.com will offer Database.com developer toolkits for Java, .Net, Ruby, PHP, iPhone, iPad, Android, Google App Engine, Windows Azure, Amazon Web Services, and Flash.

Won't Internet latency pose a problem? Salesforce admits that you aren't going to build high-performance, database-intensive transaction systems using Database.com, but the company is positioning Database.com as a back end to applications running on Amazon, Google, and elsewhere. Of course, if you build your application on Force.com, one would suppose that the physical proximity of Database.com would make latency less of an issue.

How can Salesforce offer its usual per-user pricing for a database service? It can't -- although, as with Force.com, there's a free version (for up to three users and 100,000 records and 50,000 transactions per month). Database.com costs $10 per month for each set of 100,000 records beyond that and $10 per month for each set of 150,000 transactions beyond that. Plus, there's the extra $10 per user per month for the aforementioned Enterprise Services security controls.

So why isn't Oracle offering a cloud version of Oracle Database? Oracle has been slow to embrace the cloud and Salesforce has maintained a huge, multitenanted version of Oracle's database for years. But recent speculation that Oracle will buy Salesforce seems certain to redouble. After all, wouldn't you think Oracle would want to own the Database.com domain?

Who is likely to use Database.com? As usual, large enterprises will be last in line due to the usual security paranoia, not to mention the latency problem. You can certainly imagine small businesses using it for internal purposes, if they need the functionality of an Oracle database but don't want to pay the high licensing fees. Those small players will almost certainly include mobile applications developers; few mobile apps send a lot of data back and forth over the air, so the latency effect would be minimal.

In fact, cloud application developers of any kind should be a rich target market for Database.com. The attractiveness of Oracle database functionally by the pound rather than by the license is undeniable, although every customer will have to calculate whether the latency and ongoing operational costs add up to a worthy trade-off. At the very least, Benioff has added a new term to the cloud lexicon: DaaS.